Outcome of Patients with Beta-Thalassemia Major Given Either Bone Marrow and Frozen Cord Blood of Same Sibling or Bone Marrow Transplantation from Sibling Donors

Background: Hematopoietic stem cell transplantation (HSCT) is the only curative treatment for thalassemia major (TM). Bone marrow (BM) and cord blood (CB) are biologically different stem cell sources.

Methods: We analyed the results of a retrospective study of HSCT in 29 chlidren (median age at transplantation was 6 years old) with β-TM after the combined infusion of G-CSF primed bone marrow (BM) and cord blood (CB) from the same transplantation to outcomes in children with β-TM who had received BM (n=26).Patients treated with bone marrow transplant (BMT)were closely matched to the co-transplant group in terms of age, human leucocyte antigen (HLA) matching and duration of follow-up.Compared to BMT group, the donors in co-transplant group were younger (median age 2 vs. 4 years old, p=0.015)

Results: In the co-transplant group,the mean total nucleated cells (TNC) was 2.63×10⁸/kg(range,1.26-3.72×10⁸/kg) and the CB was 0.39×10⁸/kg(range,0.27-0.71×10⁸/kg), respectively.The mean TNC (3.02 vs. 2.79×10⁸/kg, p=0.532) and CD34⁺cells (7.55 vs. 6.94×10⁶/kg, p=0.227) were insignificantly difference between the co-transplant group and BMT group. Of the 53 patients who had successful engraftment,patients who received a co-transplant had a lower incidence of ≥ grade II acute (3.3 vs. 20.8, p=0.047) and chronic(0vs.16.7%,p=0.022) graft versus host disease (GVHD) compared to BM transplant (BMT) recipients. There was no graft rejection (GR) after co-transplant, but GR happened two patients (7.7%) in BMT group(p=0.132).We found insignificant difference in neutrophils (18.7vs.19.9 days, p= 0.956) and platelet (24.7vs. 26.2 days, p=0.235) engraftment time between the co-transplant and BMT group. All patients were followed up until june 30, 2014, the 5 year probability of overall survival (OS), transplant free survival (TFS) and transplant-related mortality (TRM) were similar for the two groups. The 5-year probability of OS and TFS were 89.7% and 89.7% in the co-transplant group, 92.3%and 84.6% after BMT (P=0.740 and 0.573, respectively).

Conclusions: Our data suggest that the lower risk of GVHD is retained with co-transplant group. The incidence of GR lower in the co-transplant group, although a larger cohort of patients will be needed to confirm this inital obser-vation.Here,we suggest transplantation of G-CSF primed BM a,nd CB of same sibling appears to be a feasible and effective strategy to further optimize outcomes of HSCT for TM with decreasing the risk of the occurrence of GVHD.